Back in 2012, when Matt and I were at the American Museum of Natural History to work on Apatosaurus” minimus, we also photographed some other sacra for comparative purposes. One of them you’ve already seen — that of the Camarasaurus supremus holotype AMNH 5761. Here is another:

diplodocus-sacrum-composite

(Click through for glorious 3983 x 4488 resolution.)

This is AMNH 3532, a diplodocid sacrum with the left ilium coalesced and the right ilium helpfully missing, so we can see the structure of the sacral ribs. Top row: dorsal view, with anterior to the left; middle row, left to right: anterior, left lateral and posterior views; bottom row: right lateral view.

As a matter of fact, we’ve seen this sacrum before, too, in a photo from Matt’s much earlier AMNH visit. But only from a left dorsolateral perspective.

When we first saw this, it didn’t even occur to us that it could be anything other than good old Diplodocus. And indeed it’s a pretty good match for the same area in the CM 84/94 cast in the Museum für Naturkunde Berlin (this image extracted from Heinrich Mallison’s beautiful giant composite):

img_4853-img_4886-v3-sm-sacrum

And the general narrowness of the AMNH sacrum says Diplodocus to me. But what is that expectation of narrowness based on? When I compared the AMNH specimen with Hatcher’s (1901) ventral-view illustration in his classic Diplodocus monograph, I had second thoughts:

Hatcher (1901: fig. 9). Inferior view of sacrum and ilia of Diplodocus carnegii (No. 94), one tenth natural size; bp, public peduncle; is, ischiadic peduncle; a, anterior end; p, posterior end.

Hatcher (1901: fig. 9). Inferior view of sacrum and ilia of Diplodocus carnegii (No. 94), one tenth natural size; pp, public peduncle; is, ischiadic peduncle; a, anterior end; p, posterior end.

That is a much wider sacrum than I’d expected from Diplodocus.

So what is going on here? Is Diplodocus a fatter-assed beast than I’d realised? I am guessing not, since my expectation of narrowness has been built up across years of looking at (if not necessarily paying much attention to) Diplodocus sacra.

So could it be that CM 94, the referred specimen that Hatcher used to make up some of the missing parts of the CM 84 mount, is not Diplodocus?

Well. That is certainly now how I expected to finish this post. Funny how blogging leads you down unexpected paths. It’s a big part of why I recommend blogging to pretty much everyone. It forces you to think down pathways that you wouldn’t otherwise wander.

References

  • Hatcher, Jonathan B. 1901. Diplodocus (Marsh): its osteology, taxonomy and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1:1-63 and plates I-XIII.

 

IMG_5272

Brian Engh (bottom left, enthusing about the Ceratosaurus just off-screen) and I are recently returned to civilization after a stint of fieldwork in Utah. On the way home, we made a detour to Salt Lake to visit the new Natural History Museum of Utah.

IMG_5257

The NHMU is one of the nicest museums I’ve ever had the pleasure of roaming through. They have a ton of stuff on display, including lots of real fossils and quite a few touchable specimens, with an understandably heavy emphasis on Utah’s extensive paleontological record.

IMG_5261

The museum is also beautifully laid out – you can walk around almost all of the mounts and see most of them from multiple levels of elevation. The signage hits a new high for being both discreet and informative. Almost everything on display is clearly identified either as a cast or by specimen number (or maybe both), and the real specimens typically list both the discoverer and the preparator. I’ve never seen that before, and I like it a lot.

IMG_5290

I suppose I should say a few words about the Barosaurus mount. It’s pretty cool – you can get very close to it, walk all the way around the body, and – crucially for a true sauropod lover – count vertebrae. They gave it 16 cervicals and 9 dorsals, just as hypothesized by McIntosh (2005), and unlike the AMNH Barosaurus, which has the neck cheated out by one extra cervical.

On the left in the photo above is the famous wall of ceratopsian skulls. More about that next time.

Reference

McIntosh, J.S. 2005. The genus Barosaurus Marsh (Sauropoda, Diplodocidae); pp. 38-77 in Virginia Tidwell and Ken Carpenter (eds.), Thunder Lizards: the Sauropodomorph Dinosaurs. Indiana University Press, Bloomington, Indiana, 495 pp.

A while back, we noted that seriously, Apatosaurus is just nuts, as proven by the illustrations in Ostrom and McIntosh (1966: plate 12).

Now I’m posting those illustrations again, in a modified form, to make the same point. Here ya go:

Brontosaurus excelsus holotype YPM 1980, cervical vertebra 8, in anterior, left lateral and ventral views. Adapted from Marsh's plates in Ostrom & McIntosh (1966).

Brontosaurus excelsus holotype YPM 1980, cervical vertebra 8, in anterior, left lateral and ventral views. Adapted from Marsh’s plates in Ostrom & McIntosh (1966: plates 12-13).

Here’s what’s changed since last time:

  1. Apatosaurusexcelsus is Brontosaurus again!
  2. I cleaned up the scans of the plates, removing all the labels
  3. In the lateral view, I added a reconstruction of the missing neural spine, based on that of Apatosaurus louisae (from Gilmore 1936: plate XXIV). This reconstruction first appeared in Taylor and Wedel (2013a: figure 7).
  4. Most importantly, I added the ventral view of the vertebra from plate 13. Only now can you properly appreciate the truly bizarre shape of this bone. (The prezygs appear to project further forward than they should because the illustrated aspect is not true ventral, but slightly anteroventral.)

If only those three views were enough to construct a 3D model by photogrammetry! Sadly, it’s not possible to get photos of the whole vertebra from different angles now, as it’s tied up in the mounted Brontosaurus skeleton at the YPM:

Part of the neck of the mounted skeleton of Brontosaurus excelsus holotype YPM 1980, in right posterodorsolateral view (i.e. from behind, above, and to the right). The vertebra in the centre of the picture may well be the one illustrated above, but don't hold me to it.

Part of the neck of the mounted skeleton of Brontosaurus excelsus holotype YPM 1980, in right posterodorsolateral view (i.e. from behind, above, and to the right). The vertebra in the centre of the picture may well be the one illustrated above, but don’t hold me to it.

The bottom line: these are some crazy-ass morphologically distinctive vertebrae. Those ventrolaterally projecting processes that bear the cervical ribs are, for my money, the single most distinctive feature of apatosaurine sauropods. And they reach their zenith (or maybe their nadir, since they point downwards) in Brontosaurus. These processes are the reason that apatosaurs had Toblerone-shaped necks — triangular in cross-section, with the base flat or even concave. Any restoration that shows a tubular neck is way off base.

References

fat-necked-apatosaurs-make-the-world-go-round

The first hypothesis is that, contra Elk (1972), all Brontosauruses were rather fat at one end, then much fatter in the middle, then thin at the other end.

The second theory is that Diplodocus was dumb. Evidence is here presented in the form of an important new life restoration by Matthew Taylor.

derpolodocus

References

  • Elk, Anne. 1972. Anne Elk’s Theory on Brontosauruses. Reprinted in: Chapman, G., Cleese, J., Gilliam, T., Idle, E., Jones, T. and Palin, M. (eds). Just the Words, Volume 2. Methuen, London, 118-120.

AMNH 460 skeleton model 2

In a recent post I showed some photos of the mounted apatosaurine at the American Museum of Natural History in New York, AMNH 460, which Tschopp et al. (2015) regarded as an indeterminate apatosaurine pending further study.

A lot of museums whose collections and exhibits go back to the late 19th and early 20th centuries have scale model skeletons and sculptures that were used to guide exhibit design. I have always been fascinated by these models, partly because they’re windows into another era of scientific research and science communication, and partly because they’re just cool – basically the world’s best dinosaur toys – and I covet them. In my experience, it is very, very common to find these treasures of history buried in collections, stuck up on top of specimen cabinets, or otherwise relegated to some out-of-the-way corner where they won’t be in the way. I know that exhibit space is always limited, and these old models often reflect ideas about anatomy, posture, or behavior that we now know to be mistaken. But I am always secretly thrilled when I see these old models still on exhibit.

AMNH T rex skeleton model

The AMNH has a bunch of these things, because Henry Fairfield Osborn was crazy about ’em. He not only used 2D skeletal reconstructions and 3D model skeletons to guide exhibit design, he published on them – see for example his 1898 paper on models of extinct vertebrates, his 1913 paper on skeleton reconstructions of Tyrannosaurus, and his 1919 paper with Charles Mook on reconstructing Camarasaurus. That genre of scientific paper seems to have disappeared. I wonder if the time is right for a resurgence.

So in a glass case at the feet of AMNH 460 is a model – I’d guess about 1/12 or 1/15 scale – of that very skeleton. You can tell that it’s a model of that particular skeleton and not just some average apatosaur by looking carefully at the vertebrae. Apatosaurines weren’t all stamped from quite the same mold and the individual peculiarities of AMNH 460 are captured in the model. It’s an amazing piece of work.

AMNH 460 skeleton model

The only bad thing about it is that – like almost everything behind glass at the AMNH – it’s very difficult to photograph without getting a recursive hell of reflections. But at least it’s out where people can see and marvel at it.

Oh, and those are the cervical vertebrae of Barosaurus behind it – Mike and I spent more time trying to look and shoot past this model than we did looking at it. But that’s not the model’s fault, those Barosaurus cervicals are just ridiculously inaccessible.

So, memo to museums: at least some of us out here are nuts about your old dinosaur models, and where there’s room to put them on exhibit, they make us happy. They also give us views of the skeletons that we can’t get otherwise, so they serve a useful education and scientific purpose. More, please.

References

Osborn, H. F. (1898). Models of extinct vertebrates. Science, New Series, 7(192): 841-845.

Osborn, H.F. (1913). Tyrannosaurus, restoration and model of the skeleton. Bulletin of the American Museum of Natural History, 32: 91-92, plates 4-6.

Osborn, H. F., & Mook, C. C. (1919). Characters and restoration of the sauropod genus Camarasaurus Cope. From type material in the Cope Collection in the American Museum of Natural History. Proceedings of the American Philosophical Society, 58(6): 386-396.

AMNH 460 left anterolateral view

Apatosaurines on the brain right now.

I’ve been thinking about the question raised by Jerry Alpern, a volunteer tour guide at the AMNH, regarding the recent Tschopp et al. (2015) diplodocid phylogeny. Namely, if AMNH 460 is now an indeterminate apatosaurine, pending further study, what should the museum and its docents tell the public about it?

Geez, Apatosaurus, it’s not like we’re married!

I think it’s a genuinely hard problem because scientific and lay perspectives on facts and hypotheses often differ. If I say, “This animal is Apatosaurus“, that’s a fact if I’m talking about YPM 1860, the genoholotype of Apatosaurus ajax; it would continue to be a fact even if Apatosaurus was sunk into another genus (as Brontosaurus was for so long). We might call that specimen something else, but there would always be a footnote pointing out that it was still the holotype of A. ajax, even if the A. part was at least temporarily defunct – the scientific equivalent of a maiden name.* For every other specimen in the world, the statement, “This animal is Apatosaurus” is a hypothesis about relatedness, subject to further revision.

* This is going to sound kinda horrible, but when one partner in a marriage takes the other’s surname, that’s a nomenclatural hypothesis about the future of the relationship.

Apatosaurine cervicals are the best cervicals.

Apatosaurine cervicals are the best cervicals.

Fuzzy science

Things that look fairly solid and unchanging from a distance – specifically, from the perspective of the public – often (always?) turn out to be fairly fuzzy or even arbitrary upon closer inspection. Like what is Apatosaurus (beyond the holotype, I mean) – or indeed, what is a planet.** There is no absolute truth to quest for here, only categories and hypotheses that scientists have made up so that we can have constructive conversations about the crazy spectrum of possibilities that nature presents us. We try to ground those categories and hypotheses in evidence, but there will always be edge cases, and words will always break down if you push them too hard. Those of us who work on the ragged frontier of science tend to be fairly comfortable with these inescapable uncertainties, but I can understand why people might get frustrated when they just want to know what the damned dinosaur is called.

** Triton, the largest body orbiting Neptune, is almost certainly a captured Kuiper Belt object, and it’s bigger than Pluto. Moon or planet? Probably best to say a former dwarf planet currently operating as a satellite of Neptune – but that’s a mouthful (and a mindful, if you stop to think about it), not a short, convenient, easily-digestible label. Any short label is going to omit important information. This is related to the problem of paper title length – below some threshold, making something shorter means making it incomplete.

What I would say

I suppose the short version that is most faithful to the Tschopp et al. results is:

This skeleton (AMNH 460) might be Apatosaurus or Brontosaurus or a third, new thing – scientists aren’t sure yet.

A reasonable follow-up sentence – and an answer to the inevitable “Why not?” – would be:

They have to look at 477 anatomical details for lots of skeletons and weigh all the evidence, and that takes time.

Personally, if I was talking to museum visitors I would lean in conspiratorially and say:

If you want to call it Apatosaurus or Brontosaurus, go ahead – those are both ‘live’ hypotheses, and even the world’s experts on this problem can’t tell you that you’re guessing the wrong way – at least not yet.

And if there was a kid in the group, I’d add:

Maybe you’ll be the one to figure it out!

What would you say?

My neck is fat.

My neck is fat.

P.S. I wouldn’t change the signage. It could still turn out to be Apatosaurus, and the Tschopp et al. results do not lend themselves to easy label-ification.

P.P.S. With some modification for taxonomy, all of this applies to the Field Museum diplodocid FMNH P25112 as well.

Reference

Tschopp E, Mateus O, Benson RBJ. (2015) A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda) PeerJ3:e857 https://dx.doi.org/10.7717/peerj.857

Peggy Sue's Diner-saurs - London with sauropod

A couple of weekends ago, London and I went camping and stargazing at Afton Canyon, a nice dark spot about 40 miles east of Barstow. On the way home, we took the exit off I-15 at Ghost Town Road, initially because we wanted to visit the old Calico Ghost Town. But then we saw big metal dinosaurs south of the highway, and that’s how we came to Peggy Sue’s Diner and in particular the Diner-saur Park.

Peggy Sue's Diner-saurs - spinosaur

The Diner-saur Park is out behind the diner and admission is free. There are pools with red-eared sliders, paved walkways, grass, trees, a small gift shop, and dinosaurs. Here’s a Spinosauruscuriously popular in the Mojave Desert, those spinosaurs.

Peggy Sue's Diner-saurs - stegosaur

Ornithischians are represented by two stegosaurs, this big metal one and a smaller concrete one under a tree.

Peggy Sue's Diner-saurs - turtles

The turtles are entertaining. They paddle around placidly and crawl out to bask on the banks of the pools, and on little islands in the centers.

Peggy Sue's Diner-saurs - sign

The gift shop is tiny and the selection of paleo paraphernalia is not going to blow away any hard-core dinophiles. But it is not without its charm. And, hey, when you find a dinosaur gift shop in the middle of nowhere, you don’t quibble about size. London got some little plastic turtles and I got some cheap and horribly inaccurate plastic dinosaur skeletons to make a NecroDinoMechaLaser Squad for our Dinosaur Island D&D campaign.

Now, about that sauropod. The identification sign on the side of the gift shop notwithstanding, this is not a Brachiosaurus. With the short forelimbs and big back end, this is clearly a diplodocid. The neck is too skinny for Apatosaurus or the newly-resurrected Brontosaurus, and too long for Diplodocus. I lean toward Barosaurus, although I noticed in going back through these photos that with the mostly-straight, roughly-45-degree-angle neck, it is doing a good impression of the Supersaurus from my 2012 dinosaur nerve paper. Compare this:

Peggy Sue's Diner-saurs - sauropod 1

to this:

Wedel RLN fig1 - revised

If I had noticed it sooner, I would have maneuvered for a better, more comparable shot.

Guess I’ll just have to go back.

Reference

Wedel, M.J. 2012. A monument of inefficiency: the presumed course of the recurrent laryngeal nerve in sauropod dinosaurs. Acta Palaeontologica Polonica 57(2):251-256.

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